According to experiences of users of complex machine tools, a large number of workpieces have to be milled and lathed. This is done on separate and complete milling machines and lathes with individual program controls. Apart from the necessarily high expense, it can be difficult to optimally combine various machine types in order to achieve a flexible working process.
In addition, there are work centers which can alternatively mill or lathe a piece in one clamping. These machines, however, are either milling machines with supplementary attachments for lathe work, or lathes with milling attachments. Such attachments are naturally not as powerful as the machine's primary units, which in turn limits its usage to specific workpieces. Moreover, parallel milling or lathe work on separate workpieces is not possible.